The present invention provides an improved grip for ultrasonic inserts used with for example, magnetostrictive ultrasonic scaling devices. When used with proprietary ultrasonic scaling devices such as CAVITRON® by DENTSPLY INTERNATIONAL of York, Pa., the dental insert vibrates at an ultrasonic frequency to remove biofilm and calculus from the tooth and root surfaces while having cooling water flush away the removed deposits. The improved grip of the invention enhances softness, feel, and shape compared to the current insert grip designs in the industry. The grip is robust and resilient to the conditions of extreme temperature and pressure typical to autoclave environments, and to washer/disinfectant chemicals.
There is a trend in dentistry towards more comfortable, ergonomic equipment and instruments. A wider grip helps lessen hand fatigue to help maintain tactile sensitivity, as well as decrease the incidence of carpal tunnel syndrome.
Many useful dental instruments employ substantial vibratory motion at a tool tip of the instrument for cleaning, scaling and like operations. The tool tips are often designed to produce flexural and longitudinal vibrations with flexural motions of from about 0.02 to 0.2 mm. The tip is typically attached to an electro-mechanical part or section that can be induced to vibrate at high frequency. The instrument is driven for example, by an electronic generator at relatively high frequencies, typically on the order of above 20 kHz, to obtain adequate motion and to minimize objectionable noise since the human hearing threshold is about 18 kHz. The energy generator and related electro-mechanical section may be any one of several types such as electro-dynamic, piezo electric, or magnetostrictive. Design of the tip and its related electro-mechanical components involves combining a number of parameters to produce mechanical resonances (harmonic vibrations) at the driving frequency to produce amplified mechanical motion, particularly at the distal tip end.
In many operations employing a vibrating tip tool, it is useful and often necessary to have a source of water or other fluid impinging upon the workpiece surfaces and/or tool surfaces in order to cool them or remove debris generated by the work. For example, in dental applications, when an ultrasonically vibrated tip contacts a tooth surface, as required for performing a cleaning operation, the moving tip against the tooth surface produces heat. The patient may experience a pain sensation which can be severe if the operator applies even mild pressure against the tooth while cleaning. Water or some other fluid is usually supplied to the tooth surface in order to remove the heat and minimize pain and possible heat damage to the tooth. In addition, a number of the electro-mechanical devices utilized in providing a vibrating tip generate heat internally during operation.
An example of an ultrasonic dental tool, wherein a handpiece containing a coil applies an electro-magnetic field to a magnetostrictive insert body to which a tool tip is fixed is described by Perdreaux in U.S. Pat. No. Re. 30,536 which is hereby incorporated by reference for the general background of such devices. In the Perdreaux design, heat caused by electrical and mechanical friction losses within the tool during vibration are dissipated by means of a cooling fluid that flows axially with respect to the tool insert, over the active magnetostrictive element or stack, emerging from an annular space between the insert and the handpiece and being directed toward the working end of the tool. The arrangement is such that heat generated by the insert body warms the fluid which is then directed, as a convenient source of irrigating, flushing and/or cooling fluid, onto the active tip or workpiece area. The warm fluid minimizes reactions by patients who have sensitivity to cold temperatures.
In a number of dental operations, the vibrating tip is guided over and about tooth surfaces by the operator. The tip should be capable of penetrating between teeth and under or below the gingiva or gum line. Generally, the tip should be small in cross-section, ideally having a pointed tip with a tapered cross-section extending about 2.5 to 5 mm back from the distal tip end to allow adequate access between teeth and gingiva.
In addition, such tips are often curved or shaped to conform to or be compatible with tooth surfaces. Useful tips will curve sufficiently to permit spanning the tooth frontal surface when entrance to abutting surfaces is needed or when access to subgingival zones about the oral cavity are required.
It is often the case that an ultrasonically driven tool is configured so as to be connected to a part of the ultrasonic inducing element, such that the assembly can be inserted into a holder or handpiece or the like to complete the driving element. This is especially useful in the dental, medical or other fields where it may be necessary to clean and or sterilize the tool tip assembly apart from the remaining portions of the overall device. As an example, the FSI SLIMLINE series of ultrasonic inserts available from DENTSPLY INTERNATIONAL of York, Pa. have a tool connected to a magnetostrictive stack to form the insert. The insert is then inserted into a handpiece that provides the electrical connections to the insert to operate the thus assembled scaler device. After use, the insert can be removed from the handpiece and sterilized apart from the remaining portions of the device.
Inserts, such as the above mentioned FSI SLIMLINE inserts used to scale teeth, often have a gripping portion that's affixed to the insert such that this portion can be gripped by a user during use. It will be appreciated that such gripping portions should be configured so as to be ergonomically beneficial for the user. In the past such gripping portions have been made of various shapes and of various materials (such as Santoprene) to promote such comfort. These designs and materials of construction must be chosen to withstand the repeated sterilization procedures which often include the use of high heat exposure.
According to the present invention, the grip shape provides a finger rest preventing index or middle finger, depending on fulcrum, from slipping off insert. As a result the clinician can maintain a light grip and focus more on tip to tooth adaptation to improve both patient comfort and overall ergonomics. A one-piece grip is designed to enable easier cleaning. Grip texture is specially designed to lesson chance of slipping. Larger grip diameter is designed to lesson muscle load and pinch force. Grip texture is specially designed to increase friction with fingers, thereby requiring less pinching force.
Many current ultrasonic scaler inserts in the industry rely on a two part assembly that utilizes an ultrasonic weld to produce both a hermetic seal and a primary means of attachment in order to secure the plastic mold hand grip to the insert connecting body. The plastic molded parts must maintain a fluid tight seal and create an internal gland for a distal o-ring to seal between the connecting body and plastic molded halves of the grip. Users expect the dental insert to wear out, however prior to tips of the dental insert wearing beyond their usefulness, a water leak may develop which can make it difficult to maintain a proper grip (i.e. wet fingers) and irritate the patient by dripping water onto their face. The present Invention utilizes a construction that features a one-piece grip portion and which has separate features to secure the assembly and produce a hermetic seal.
As stated, current methods of assembling a grip onto an ultrasonic dental insert often include welding two substantially mirror image halves together using ultrasonic energy or the like. The ultrasonic welding operation uses friction to heat and melt the opposing plastic halves to form a joint. During the welding operation flash is squeezed out of the weld joint and requires removal. Removal includes a tedious manual step that has been eliminated in the invention disclosed herein. Beyond creating a cosmetic issue, the excess flash that is squeezed to the inside of the grip can allow flash particles to clog the fluid path.
It is evident from the state of the art that a new ultrasonic insert for use in vibratory activated tools would be desirable that includes an ergonomic gripping portion made without the previous disadvantageous welding procedures.